However, mobile shoppers spent more with pureplays at £82 (US$138) per transaction - an 8% rise in the first half of this year - versus £80 (US$135) for retailers (5% rise) that have a website and a physical store.

"We saw earlier this year that a third of online retail sales are now made on a mobile device and the figure is only set to rise as the technology becomes increasingly more sophisticated," said Alex Smith-Bingham, Capgemini vice president and digital services leader.

"It would appear that the multichannel retailers, which have been investing in their mobile platforms, have a larger opportunity than their pureplay counterparts as mobile is not only an additional sales channel but can also drive greater engagement and sales in-store."